Container closures, and more specifically, tamper-indicating or tamper-evident closures are well known in the art. Such closures enable a user to determine whether the container has been previously opened. Various types of tamper-indicating arrangements are known in the art. Many such arrangements include depending tamper-indicating bands. Most of these bands include an inwardly extending portion or projection that engages a locking collar or like annular projection extending from the container finish.
Although such tamper-indicating closures function well for their intended purposes, they can be difficult to manufacture, e.g., mold, without the band separating from the cap after the closure is molded when removing it from the molding apparatus. Moreover, due to the relatively tight tolerances necessary to assure proper function of the closure, such bands can separate from the closure upon initial application (i.e., capping) of the closure onto the container as a result of passing the band over the container threads and locking collar. Further, when a band is too flimsy, or the tolerances too loose, tamper-evident function may be circumvented when the closure can be removed intact after having been applied.
One alternative method of manufacture is to mold the cap and the band separately and use a weld or an adhesive to secure the band to the cap. Such methods complicate the manufacturing processes by requiring the molding of a larger number of parts, and similarly complicate assembly by requiring an adhesion process. Simplicity and reliability of manufacture and assembly are facilitated by forming the closure as a single piece, and applying it to the associated container in a single step.
Another common closure arrangement presents a rounded locking collar in combination with a rounded band, which enables the band to slip over the locking collar for assembly of the closure. Such rounded bands and locking collars present sliding interacting or engaging surfaces which may fail to offer positive locking of the band and the locking collar after assembly. If the tamper-evident band slips over the locking collar, such slippage can result in failure of the tamper-indicating features if the tamper-evident band is completely removed with the cap, without separating from the cap (i.e. unbroken).
Another alternative method that is used to form tamper-indicating closures is to fold, bend, score or crease the beads, wings or tabs (on the inside of the band) after formation, before (and sometimes during) applying the closure to the container. This approach, however, presents limitations similar to closures that are formed by welding--the tamper joint between evident ring, and the cap is not as strong as closures that are formed as one piece. Such welding or manipulation weakens the plastic of the tamper evident band. An unfortunate compromise arising from this solution is that the tamper evident band is more likely to be damaged while being removed from the mold or while being placed on the container. Further, such weakening can make the tamper evident band more prone to accidental separation from the container cap. Such failures can result in containers which appear to have been tampered with, although they have not.
Accordingly, there exists a need for a stronger, readily formed closure that positively locks onto its associated container intact. The stronger closure also resists flexing or bending, and possible failure of the tamper-indicating band during application of the cap onto the container. The closure also resists accidental separation of the tamper-evident band from the cap during shipping, and stocking. In such a closure, the surfaces of the tamper evident band and the locking collar positively lock, and do not present inclined, arcuate, or radial surfaces to each other that could otherwise facilitate slippage of the tamper-evident band. Preferably, such a closure is molded as a single piece in the position of function to preserve the strength of the closure material, without bending or creasing the material, and without the use of adhesives or welding.